Flexible tip catheter

ABSTRACT

A catheter may include an inner liner, at least one support structure over the inner liner, and an outer jacket over the at least one support structure. In some examples, the catheter includes a tip jacket positioned over a distal portion of the outer jacket and extend beyond a distal-most part of the inner liner and a distal-most part of the outer jacket to define a single-layer catheter tip. In some examples, the at least one support structure may include a braid and a coil. The catheter may include a marker band over a distal portion of one of the braid or the coil. The other of the braid or the coil ends proximally of a proximal end of the marker band, such that the catheter includes a location with lower radial and/or flexural stiffness proximal of the marker band.

TECHNICAL FIELD

This disclosure relates to a medical catheter.

BACKGROUND

A medical catheter defining at least one lumen has been proposed for usewith various medical procedures. For example, in some cases, a medicalcatheter may be used to access and treat defects in blood vessels, suchas, but not limited to, lesions or occlusions in blood vessels.

SUMMARY

In some aspects, the disclosure describes a medical catheter(“catheter”) that includes at least one feature that reduces a chance oftraumatic contact between a tip of the catheter and tissue, such as awall of vasculature of a patient. In some examples, the catheter mayinclude an inner liner, at least one support structure over the innerliner, an outer jacket over the at least one support structure, and atip jacket. The tip jacket may be positioned over a distal portion ofthe outer jacket and extend beyond a distal-most part of the inner linerand a distal-most part of the outer jacket. The tip jacket thus maydefine a single-layer catheter tip. A radially outer surface of the tipjacket may taper radially inward as the tip jacket extends distally,which may reduce the cross-sectional area of the catheter at the distaltip of the catheter and aid navigation of the catheter throughvasculature of a patient. Forming the distal tip of the catheter from asingle layer of material (e.g., by at least excluding the inner linerand the outer jacket from the distal tip) may enable the distal tip tobe more acutely tapered, which may also aid navigation of the catheterthrough vasculature of a patient. The material from which the tip jacketis formed may be the same or a lower durometer than the material fromwhich the inner liner is formed and the material from which the outerjacket is formed. In this way, the tip jacket may be more atraumaticthan a catheter in which the inner liner, the outer jacket, or bothextend to a distal end of the catheter.

In some aspects, the disclosure describes a catheter that includes aphysical configuration that results in a preferential bending locationproximal of a marker band. The catheter may include an inner liner, abraid over the inner liner, a coil over the inner liner, and an outerjacket over the at least one support structure. The catheter also mayinclude a marker band over a distal portion of one of the braid or thecoil. The other of the braid or the coil ends proximally of a proximalend of the marker band. By ending one of the braid or the coilproximally of the proximal end of the marker band, the catheter includesa location with lower radial and/or flexural stiffness proximal of themarker band. Thus, the catheter may preferentially bend at this locationin response to a distal tip of the catheter contacting an anatomicalstructure, such as a wall of vasculature of a patient. This may alsocontribute to navigability of the catheter through vasculature and makethe catheter more atraumatic than a catheter that does not include thepreferential bending location proximal of the marker band. In someexamples, a catheter may include both a distal tip formed from a single,relatively soft tip jacket and a preferential bending location proximalof the marker band. In other examples, a catheter may include only oneof the distal tip formed from a single, relatively soft tip jacket orthe preferential bending location proximal of the marker band.

Clause 1: A catheter including an elongated body including proximal anddistal portions, the distal portion of the elongated body comprising: aninner liner; at least one support structure positioned over the innerliner; an outer jacket positioned over the at least one supportstructure, wherein the outer jacket tapers radially inward distal of adistal-most part of the at least one support structure to bond to theinner liner; and a tip jacket positioned over a distal part of the outerjacket and extending beyond a distal-most part of the inner liner andthe outer jacket to define a single-layer catheter tip, wherein the tipjacket comprises a material that is the same or a lower durometer thanthe inner liner and the same or a lower durometer than the outer jacket.

Clause 2: The catheter of clause 1, wherein the tip jacket comprises apolyurethane, a polyolefin elastomer, a poly(ether-block-amide), orcombinations thereof.

Clause 3: The catheter of clause 1 or 2, wherein the tip jacket materialhas a durometer of 35 D or less.

Clause 4: The catheter of any one of clauses 1 to 3, wherein the tipjacket is the only layer for the distal-most 0.3 to 0.8 millimeters ofthe catheter.

Clause 5: The catheter of any one of clauses 1 to 4, wherein the innerliner and the outer jacket extend distally past the distal-most part ofthe at least one support structure by about 0.2 millimeters to about 0.6millimeters.

Clause 6: The catheter of any one of clauses 1 to 5, further comprisinga marker band, wherein the marker band is positioned over the at leastone support structure near the distal-most part of the at least onesupport structure.

Clause 7: The catheter of any one of clauses 1 to 6, wherein the atleast one support structure comprises at least one of a braid or a coil.

Clause 8: The catheter of any one of clauses 1 to 7, wherein the atleast one support structure comprises a braid and a coil.

Clause 9: The catheter of clause 8, wherein the braid is positioned overthe coil.

Clause 10: The catheter of clause 8, wherein the coil is positioned overthe braid.

Clause 11: The catheter of clause 8, further comprising a marker band,wherein the marker band is positioned over one of the braid or the coilnear the distal-most part of the one of the braid or the coil, andwherein the other of the braid or the coil ends proximally of a proximalend of the marker band.

Clause 12: The catheter of clause 11, wherein the other of the braid orthe coil ends at least about 0.5 millimeters proximally of the proximalend of the marker band.

Clause 13: An assembly comprising: the catheter of any one of clauses 1to 12; and an aspiration pump connected to the catheter.

Clause 14: A method of forming an elongated body of a catheter, themethod comprising: positioning at least one support structure over aninner liner; positioning an outer jacket over the at least one supportstructure, wherein a distal part of the outer jacket extends past adistal-most part of the at least one support structure to taper radiallyinward distal of the distal-most part of the at least one supportstructure and contact a distal part of the inner liner; and bonding atleast the distal part of the outer jacket to the distal part of theinner liner; positioning a tip jacket over the distal part of the outerjacket, wherein the tip jacket extends beyond a distal-most part of theinner liner and the outer jacket to define a single-layer catheter tip,wherein the tip jacket comprises a material that is the same or a lowerdurometer than the inner liner and the same or a lower durometer thanthe outer jacket; and bonding the tip jacket to the outer jacket.

Clause 15: The method of clause 14, wherein the tip jacket comprises apolyurethane, a polyolefin elastomer, a poly(ether-block-amide), orcombinations thereof.

Clause 16: The method of clause 14 or 15, wherein the tip jacketmaterial has a durometer of 35 D or less.

Clause 17: The method of any one of clauses 14 to 16, wherein the tipjacket is the only layer for the distal-most 0.3 to 0.8 millimeters ofthe catheter.

Clause 18: The method of any one of clauses 14 to 17, wherein the innerliner and the outer jacket extend past the distal-most part of the atleast one support structure by about 0.2 millimeters to about 0.6millimeters.

Clause 19: The method of any one of clauses 14 to 18, further comprisingpositioning a distal marker band over the at least one support structurenear the distal-most part of the at least one support structure prior topositioning the outer jacket over the at least one support structure.

Clause 20: The method of any one of clauses 14 to 19, wherein the atleast one support structure comprises at least one of a braid or a coil.

Clause 21: The method of any one of clauses 14 to 20, wherein the atleast one support structure comprises a braid and a coil.

Clause 22: The method of clause 21, wherein positioning the at least onesupport structure over the inner liner comprises positioning the braidover the coil.

Clause 23: The method of clause 21, wherein positioning the at least onesupport structure over the inner liner comprises positioning the coilover the braid.

Clause 24: The method of clause 21, further comprising positioning adistal marker band over one of the braid or the coil, and wherein theother of the braid or the coil ends proximally of a proximal end of themarker band.

Clause 25: The method of clause 24, wherein the other of the braid orthe coil ends at least about 0.5 mm proximally of the proximal end ofthe marker band.

Clause 26: A catheter comprising: an elongated body including proximaland distal portions, the distal portion of the elongated bodycomprising: an inner liner; a first support structure positioned overthe inner liner; a second support structure positioned over the firstsupport structure; a distal marker band positioned over a distal part ofone of the first support structure or the second support structure,wherein the other of the first support structure or the second supportstructure ends proximally of a proximal end of the distal marker band;and an outer jacket positioned over the first support structure, thesecond support structure, and the marker band, wherein the outer jackettapers radially inward distal of a distal-most part of the marker bandto bond to the inner liner.

Clause 27: The catheter of clause 26, wherein the first supportstructure comprises a coil and the second support structure comprises abraid.

Clause 28: The catheter of clause 27, wherein a distal end of the braidis proximal to the proximal end of the distal marker band.

Clause 29: The catheter of clause 27, wherein a distal end of the coilis proximal to the proximal end of the distal marker band.

Clause 30: The catheter of clause 26, wherein the first supportstructure comprises a braid and the second support structure comprises acoil.

Clause 31: The catheter of clause 30, wherein a distal end of the braidis proximal to the proximal end of the distal marker band.

Clause 32: The catheter of clause 30, wherein a distal end of the coilis proximal to the proximal end of the distal marker band.

Clause 33: The catheter of any one of clauses 26 to 32, wherein theother of the first support structure or the second support structureends at least about 0.5 millimeters proximally of the proximal end ofthe marker band.

Clause 34: The catheter of any one of clauses 26 to 33, wherein theother of the first support structure or the second support structureends between about 0.5 millimeters and about 5 millimeters proximally ofthe proximal end of the marker band.

Clause 35: An assembly comprising: the catheter of any one of clauses 26to 34; and an aspiration pump connected to the catheter.

Clause 36: A method of forming an elongated body of a catheter, themethod comprising: positioning a first support structure over the innerliner; positioning a second support structure over the first supportstructure; positioning a distal marker band over a distal part of one ofthe first support structure or the second support structure, wherein theother of the first support structure or the second support structureends proximally of a proximal end of the distal marker band; positioningan outer jacket over the first support structure, the second supportstructure, and the distal marker band, wherein a distal part of theouter jacket extends past a distal-most part of the marker band to taperradially inward distal of the distal-most part of the marker band andcontact a distal part of the inner liner; and bonding at least thedistal part of the outer jacket to the distal part of the inner liner.

Clause 37: The method of clause 36, further comprising: positioning atip jacket over the distal part of the outer jacket, wherein the tipjacket extends beyond a distal most part of the inner liner and theouter jacket to define a single-layer catheter tip, wherein the tipjacket comprises a material that is the same or a lower durometer thanthe inner liner and the same or a lower durometer than the outer jacket;and bonding the tip jacket to the outer jacket.

Clause 38: The method of clause 36, wherein the first support structurecomprises a coil and the second support structure comprises a braid.

Clause 39: The method of clause 38, wherein a distal end of the braid isproximal to the proximal end of the distal marker band.

Clause 40: The method of clause 38, wherein a distal end of the coil isproximal to the proximal end of the distal marker band.

Clause 41: The method of clause 37, wherein the first support structurecomprises a braid and the second support structure comprises a coil.

Clause 42: The method of clause 41, wherein a distal end of the braid isproximal to the proximal end of the distal marker band.

Clause 43: The method of clause 41, wherein a distal end of the coil isproximal to the proximal end of the distal marker band.

Clause 44: The method of any one of clauses 37 to 43, wherein the otherof the first support structure or the second support structure ends atleast about 0.5 millimeters proximally of the proximal end of the markerband.

Clause 45: The method of any one of clauses 37 to 43, wherein the otherof the first support structure or the second support structure endsbetween about 0.5 mm and about 5 mm proximally of the proximal end ofthe marker band.

Clause 46: A method comprising: inserting the catheter of any one ofclauses 1 to 12 into vasculature of a patient; and aspirating a thrombusfrom the vasculature using the catheter.

Clause 47: A method comprising: inserting the catheter of any one ofclauses 26 to 34 into vasculature of a patient; and aspirating athrombus from the vasculature using the catheter.

The details of one or more aspects of the disclosure are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the techniques described in this disclosurewill be apparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual side elevation view of an example catheter, whichincludes an elongated body and a hub.

FIG. 2 is a conceptual axial cross-sectional view of the distal portionof the elongated body of FIG. 1, where the cross-section is takenthrough a center of the elongated body along a longitudinal axis of theelongated body.

FIG. 3 is another conceptual axial cross-sectional view of a distalportion of another example catheter, where the cross-section is takenthrough a center of the elongated body along a longitudinal axis of theelongated body.

FIG. 4 is another conceptual axial cross-sectional view of a distalportion of another example catheter, where the cross-section is takenthrough a center of the elongated body along a longitudinal axis of theelongated body.

FIG. 5 is a flow diagram of an example technique for forming a catheterdescribed herein.

FIG. 6 is a flow diagram of an example technique for forming a catheterdescribed herein.

DETAILED DESCRIPTION

Medical catheters (“catheters”) described herein include at least onefeature that reduces a chance of traumatic contact between a tip of thecatheter and a tissue, such as a wall of vasculature of a patient, aidsnavigability of the catheter through vasculature of a patient, or both.Catheters include at least internal lumen through which a medical deviceor a therapeutic substance may be delivered to a target location in apatient, through which material may be aspirated from a blood vessel orother part of a patient, or the like. The diameter of the internal lumenaffects an outer diameter of the catheter. Catheters with largerinternal lumen diameters (and thus larger external diameters) areincreasingly being used to deliver treatment to target locationsaccessed through smaller, more distal, or tortuous vasculature. Forexample, catheters with larger external diameters may be used to treatacute ischemic stroke, pulmonary embolisms, or the like. The largerexternal diameter may present difficulties when tracking throughtortuous distal vasculature, such as the internal carotid and middlecerebral arteries in the intracranial space. For example, largerdiameter catheters may get caught on branching arteries while beingadvanced through the primary artery. Catheters with stiff or relativelyblunt tips may increase a chance for traumatic contact between thecatheter tip and walls of the vasculature.

In accordance with some aspects of this disclosure, a catheter mayinclude an inner liner, at least one support structure over the innerliner, an outer jacket over the at least one support structure, and atip jacket. The tip jacket may be positioned over a distal portion ofthe outer jacket and extend beyond a distal-most part of the inner linerand a distal-most part of the outer jacket (e.g., extend longitudinallybeyond the distal-most part of the inner liner and the distal-most partof the outer jacket). The tip jacket thus may define a single-layercatheter tip. A radially outer surface of the tip jacket may taperradially inward as the tip jacket extends distally, which may reduce thecross-sectional area of the catheter at the distal tip of the catheterand aid navigation of the catheter through vasculature of a patient.Forming the distal tip of the catheter from a single layer of materialmay enable the distal tip to be more acutely tapered (e.g., withoutdecreasing a cross-sectional dimension of an inner lumen of thecatheter), which may also aid navigation of the catheter throughvasculature of a patient. The material from which the tip jacket isformed may be the same or a lower durometer than the material from whichthe inner liner is formed and the material from which the outer jacketis formed. In this way, the tip jacket may be more atraumatic than acatheter in which the inner liner, the outer jacket, or both extend to adistal end of the catheter.

The disclosure also describes a catheter that includes a physicalconfiguration that results in a preferential bending location proximalof a marker band. The catheter may include an inner liner, a braid overthe inner liner, a coil over the inner liner, and an outer jacket overthe at least one support structure. The catheter also may include amarker band over a distal portion of one of the braid or the coil. Theother of the braid or the coil ends proximally to a proximal end of themarker band. By ending one of the braid or the coil proximally to theproximal end of the marker band, the catheter includes a location withlower radial and/or flexural stiffness proximal of the marker band.Thus, the catheter may preferentially bend at this location in responseto a distal tip of the catheter contacting an anatomical structure, suchas a wall of vasculature of a patient. This may also contribute tonavigability of the catheter through vasculature and make the cathetermore atraumatic than a catheter that does not include the preferentialbending location proximal of the marker band.

In some examples, a catheter may include both a distal tip formed from asingle, relatively soft tip jacket and a preferential bending locationproximal of the marker band. In other examples, a catheter may includeonly one of the distal tip formed from a single, relatively soft tipjacket or the preferential bending location proximal of the marker band.

Although primarily described as being used to reach relatively distalvasculature sites, the catheters described herein may readily beconfigured to be used with other target tissue sites. For example, thecatheters may be used to access tissue sites throughout the coronary andperipheral vasculature, the gastrointestinal tract, the urethra,ureters, Fallopian tubes and other body lumens.

FIG. 1 is a conceptual side view of an example catheter 10, whichincludes elongated body 12 and a hub 14 positioned at a proximal end 12Aof elongated body 12. In some examples, catheter hub 14 may define anopening through which an inner lumen 24 (shown in FIG. 2) of elongatedbody 12 may be accessed and, in some examples, closed. For example,catheter hub 14 may include a luer connector for connecting to anotherdevice, a hemostasis valve, or another mechanism or combination ofmechanisms for establishing connections between catheter 10 and otherdevices. In other examples, the proximal end of catheter 10 can includeanother structure in addition to or instead of hub 14.

Elongated body 12 extends from proximal end 12A to distal end 12B anddefines a proximal portion 17A and a distal portion 17B. Elongated body12 may define at least one inner lumen that extends the length ofelongated body 12. In the example shown in FIG. 1, proximal end 12A ofelongated body 12 is received within or attached to hub 14 and can bemechanically connected to hub 14 via an adhesive, welding, friction fit,or another suitable technique or combination of techniques. Hub 14defines an opening 15 located at proximal end 14A of hub 14. Opening 15is substantially aligned with inner lumen 24 of elongated body 12, suchthat inner lumen 24 may be accessed via opening 15. In some examples,catheter 10 may include a strain relief body 11, which may be a part ofhub 14 or may be separate from hub 14.

In some cases, a clinician may steer catheter 10 through the vasculatureof a patient by pushing or rotating hub 14 to navigate distal portion17B of elongated body 12 through the vasculature of a patient. Theclinician may apply torque to hub 14 and/or proximal portion 17A of thecatheter 10 (or at least a portion of elongated body 12 that is moreproximal than distal portion 17B inserted in the patient) to rotatedistal portion 17B of catheter 10.

As described further below, elongated body 12 includes an inner liner,at least one support structure, and an outer jacket, which may configureelongated body 12 to transmit the torque applied to a relativelyproximal portion to a relatively distal portion of elongated body 12. Insome examples, as shown in FIG. 2, at least distal portion 17B ofelongated body 12 includes an inner liner, at least one supportstructure, and an outer jacket. Distal portion 17B of elongated body 12also may include a tip jacket. The tip jacket may be positioned over adistal portion of the outer jacket and extend beyond a distal-most partof the inner liner and a distal-most part of the outer jacket (e.g.,extend longitudinally beyond the distal-most part of the inner liner andthe distal-most part of the outer jacket). The tip jacket thus maydefine a single-layer tip of catheter 10. A radially outer surface ofthe tip jacket may taper radially inward as the tip jacket extendsdistally, and the tip jacket may be formed from a material that is thesame or a lower durometer than the material from which the inner lineris formed and the material from which the outer jacket is formed. Inthis way, the tip jacket may be more atraumatic than a catheter in whichthe inner liner, the outer jacket, or both extend to a distal end ofcatheter 10.

In some examples, in addition to or as an alternative to thesingle-layer tip jacket, catheter 10 includes a physical configurationthat results in a preferential bending location proximal of a markerband of catheter 10. For example, as shown in FIGS. 3 and 4, catheter 10may include an inner liner, a coil over the inner liner, a braid overthe inner liner, and an outer jacket over the coil and the braid.Catheter 10 also may include a marker band. In some examples, the markerband is over a distal portion of one of the braid or the coil. The otherof the braid or the coil ends proximally of a proximal end of the markerband. In other examples, both the braid and the coil end proximally ofthe proximal end of the marker band. By ending one of the braid or thecoil proximally of the proximal end of the marker band, catheter 10includes a location with lower radial and/or flexural stiffness proximalof the marker band. Catheter 10 may preferentially bend at this locationin response to a distal tip of catheter 10 contacting an anatomicalstructure, such as a wall of vasculature of a patient, or otherwiseencountering a force oriented oblique or transverse to the longitudinalaxis of catheter 10. In other examples, the marker band is over both adistal portion of the braid and a distal portion of the coil.

In some examples, catheter 10 may be a guide catheter that acts as aconduit to help support a microcatheter. In other examples, catheter 10may be a microcatheter. In either example, elongated body 12 of catheter10 may define at least one inner lumen extending between proximal end12A and distal end 12B of elongated body (e.g., one inner lumen, twoinner lumens, three inner lumens, or more than three inner lumens). Theat least one inner lumen may open to an exterior of elongated body 12 atdistal opening 13. The at least one inner lumen may be configured toreceive one or more medical devices, serve as a conduit for the deliveryof a medical device to a distal tissue site, serve as a conduit for thedelivery of a therapeutic agent to a distal tissue site, remove thrombus(e.g., by aspiration) from the patient's vasculature, or the like.Example therapeutic agents include, but are not limited to, anoxygenated medium or a pharmaceutical agent, which may be, for example,a vasodilator such as nifedipine or sodium nitroprusside, or a tissueplasminogen activator (t-PA), which can be used to break down bloodclots.

In examples in which an inner lumen defined by elongated body 12 is usedto remove thrombus from vasculature, catheter 10 may be referred to asan aspiration catheter. A vacuum may be applied to proximal end 12A ofelongated body 12 (e.g., at opening 15) to draw a thrombus into theinner lumen via distal opening 13. An aspiration catheter may be used ina medical procedure to treat an ischemic insult, which may occur due toocclusion of a blood vessel that deprives brain tissue ofoxygen-carrying blood. In some examples, in addition to being configuredto be navigated to relatively distal tissue sites, an aspirationcatheter may also include a distal tip that is configured tosubstantially maintain its shape, even in the presence of the vacuumforce applied to the catheter during the aspiration process.

In some examples, elongated body 12 may be used to access relativelydistal vasculature locations in a patient, such as the internal carotidartery or middle cerebral artery (MCA) in a brain of a patient. The MCA,as well as other vasculature in the brain or other relatively distaltissue sites (e.g., relative to the vasculature access point), may berelatively difficult to reach with a catheter, due at least in part tothe tortuous pathway (e.g., comprising relatively sharp twists and/orturns) through the vasculature to reach these tissue sites.

Distal portion 17B of catheter 10 may be configured to be relativelyflexible to allow for navigability of elongated body 12 through atortuous vasculature of a patient. Further, catheter 10 may include adistal tip at distal end 12B that is relatively atraumatic, e.g., due toinclusion of a relatively soft, single layer tip jacket, a preferentialbending location proximal of a marker band of catheter 10, or both. FIG.2 shows a conceptual axial cross-sectional view of distal portion 20B ofan example catheter 20, where the cross-section is taken through acenter of elongated body 22 along a longitudinal axis 26. As shown inFIG. 2, elongated body 22 includes an inner liner 28, at least onesupport structure, and an outer jacket 32.

Inner liner 28 may extend from a proximal end of catheter 20 (e.g.,proximal end 12A of catheter 10 of FIG. 1) to near but proximal to adistal end 30 of catheter 20. In some examples, inner liner 28 is aunitary structure that includes a single material and single geometryalong the length of inner liner 28. In other examples, inner liner 28may include multiple sections, such as a proximal section, an optionalintermediate section, and a distal section formed from differentmaterials such that the distal liner section has a lower hardness andhigher flexibility compared to the proximal liner section. Reducing thehardness and increasing the flexibility of the distal liner sectioncompared to the proximal liner section may improve the navigability ofcatheter 20 without compromising or reducing the structural integrity(e.g., pushability) of elongated body 22.

Inner liner 28 defines inner lumen 24 of elongated body 22, inner lumen24 extending from the proximal end of elongated body 22 (e.g., proximalend 12A of FIG. 1) to distal end 30 and defining a passageway extendingfrom the proximal end to distal opening 34 at distal end 30 of elongatedbody 22. Inner lumen 24 may be sized to receive a medical device (e.g.,another catheter, a guidewire, an embolic protection device, a stent, athrombectomy device, or any combination thereof), a therapeutic agent,or the like. In some examples, inner lumen 24 has a constantcross-sectional dimension (e.g., a diameter) along a length of catheter20. In other examples, inner lumen 24 has a varying cross-sectionaldiameter, e.g., lumen 24 may taper from a larger diameter in a proximalportion of catheter 20 to a smaller diameter in a more distal portion ofcatheter 20.

Inner liner 28 may be composed of one or more different materialsincluding, for example, one or more thermoplastic elastomers such aspolyolefin elastomers, thermoplastic polyolefins, fluoropolymers such aspolytetrafluoroethylene (PTFE), perfluoroalkyoxy alkane (PFA),fluorinated ethylene propylene (FEP), or the like. In examples in whichinner liner 28 include multiple sections, the different sections mayinclude similar polymeric constructions whose relative amounts and/oradditives have been altered to result in sections of different relativehardnesses. In some examples in which inner liner 28 includes multiplesections, the respective sections can be formed as independent tubularsections that are subsequently joined together using any suitabletechnique, such as an adhesive, fusing/welding, or any combinationthereof.

In some examples, inner liner 28 may include materials that exhibit highlubricity and a Shore D hardness (ASTM D2240) of between about 25 andabout 65, such as about 55. In some examples, inner liner 28 may includea non-etched PTFE, e.g., may consist essentially of a non-etched PTFE.PTFE may exhibit a relatively high lubricity, such that the innersurface of inner liner 28 may exhibit a relatively low coefficient offriction to facilitate the introduction and passage of a medical device(e.g., another catheter, a guidewire, an embolic protection device, astent, a thrombectomy device, or any combination thereof) through innerlumen 24. In some examples, inner liner 28 may include PTFE such asTeflon® PTFE 640 available from The Chemours Company, Inc. having aShore D hardness of about 58 D. In some examples, inner liner 28 mayinclude one or more polyolefins including, for example, a polyolefinelastomer such as Engage™ polyolefin elastomers available from the DowChemical Company of Midland, Mich.

In some examples in which inner liner 28 includes a polyolefin or arelatively softer polymer, inner liner 28 may include one or more slipagents. The one or more slip agents may help increase the lubricity ofinner liner 28 which can help improve the navigability of catheter 10 byfacilitating the smooth passage of inner liner 28 over a guide catheteror guidewire. Suitable slip agents may include, for example, an amidederived from a monosaturated fatty acid such as Ampacet 100329 slipconcentrate available from Ampacet Corporation of Tarrytown, N.Y.Ampacet 100329 is characterized as 5 weight percent (wt. %) erucamide inmetallocene linear low-density polyethylene. The slip agent may be addedto the polymeric materials that form inner liner 28 in an amount ofabout 0.1 wt. % to about 1 wt. %. The slip agent may be mixed andextruded along with the thermoplastic elastomer (e.g., a polyolefinelastomer ethylene butane) used to form inner liner 28.

Elongated body 22 may include one or more support structures positionedover inner liner 28. In some examples, the one or more supportstructures may include a first support structure 36 and a second supportstructure 38. First support structure 36 may include a coil and secondsupport structure 38 may include a braid, or vice versa, or firstsupport structure 36 and second support structure 38 may each includecoils, the coils being counter-wound relative to each other. First andsecond support structures 36 and 38 may be structurally configured to berelatively flexible, pushable, navigable, and relatively kink- andbuckle-resistant, so that elongated body 22 may resist buckling when apushing force is applied to a relatively proximal portion of catheter 20to advance elongated body 22 distally through vasculature, and so thatit may resist kinking when traversing around a tight turn in thevasculature. Unwanted kinking and/or buckling of elongated body 22 mayotherwise hinder a clinician's efforts to push the elongated body 22distally, e.g., past a turn.

In some examples, the structural characteristics of first and secondsupport structures 36 and 38 may be tailored to increase the structuralintegrity of elongated body 22 while allowing elongated body 22 toremain relatively flexible. For example, first and second supportstructures 36 and 38, together with inner liner 28 and outer jacket 32,may help distribute pushing and rotational forces along a length ofelongated body 22, while also providing structural support to helpprevent kinking or buckling of elongated body 22 upon bending orrotation of elongated body 22. As a result, a clinician may applypushing forces, rotational forces, or both, to a proximal portion ofelongated body 22, and such forces may cause a distal portion ofelongated body 22 to advance distally, rotate, or both, respectively. Insome examples, rather than including both first and second supportstructures 36 and 38, catheter 20 may include only one of first andsecond support structures 36 and 38, e.g., may include only a braid oronly a coil.

In some examples, second support structure 38 may include a braidedstructure having wires or filaments of different diameters, differentcross-sectional shapes, different materials, or any combination thereof.In some cases, a braided combination of round wires and flat wires mayprovide elongated body 22 with better ovalization resistance and tensilestrength compared to other catheter designs (e.g., a support structureconsisting of only one metal coil or a braid consisting of only roundwires). For example, including second support structure 38 made of aneight-wire braid (e.g., four round wires woven against four flat wiressuch that the round wires do not cross another round wire) may providefor greater kink and ovalization resistance compared to a single coilconstruction of comparable thickness without adding to the thickness orthe tubular wall. Additionally, the combination of round wires and flatwires may contribute to a relatively thin jacket thickness and/orsidewall thickness for catheter 20 while still providing a high tensilestrength with kink resistance and pushability.

Though second support structure 38 is primarily described as a braidedstructure of different diameter wires, in some examples, second supportstructure 38 may include a wire braid of similarly sized wires (e.g.wires with similar cross-sectional sizes), round or flat filaments madeof synthetic or polymeric materials (e.g., non-metal wires), orcombinations thereof.

In some examples, in addition to or instead of second support structure38 including a braided structure, first support structure 36 may includea coil structure. The coil structure (e.g., wire coils) may exhibitcolumnar strength (e.g., kink resistance) and/or hoop strength (e.g.,resistance to ovalization). The coil structure forming first supportstructure 36 may define a plurality of turns in the shape of a helicalcoil, the coil defining a central axis substantially aligned orcoincident with longitudinal axis 26. In some examples in which firstsupport structure 36 includes more than one coil structure, the coilsmay be interspaced with each other in a longitudinal direction (in adirection along longitudinal axis 26) such that the helical coils arewound in the same direction (e.g., a right-handed wind or a left-handedwind) with one turn (e.g., one full circumvolution about inner liner 28)of a respective coil is positioned between an adjacent turn of the othercoil so that the turns of both coils are longitudinally offset from oneanother along the length of elongated body 22 and the coils do notoverlap along the length of elongated body 22. In some examples, theinterspaced arrangement of the more than one coil structures may allowfor improved rotational responsiveness and structural integrity.

First and second support structures 36 and 38 may be formed from anysuitable structural material, including, for example, a metal, an alloy,or a polymer. Suitable materials include, for example, one or moremetals such as nickel titanium alloy (e.g., Nitinol, tertiary Nitinols),stainless steel, tungsten, titanium, gold, platinum, palladium,tantalum, silver, or a nickel-chromium alloy, a cobalt-chromium alloy,or the like. In some examples, one or both of first and second supportstructures 36 and 38 may be selected to include a radiopaque material(s)to allow elongated body 22 to be easily observed by the clinician ascatheter 20 is advanced through the vasculature of a patient. In someexamples one or both of first and second support structures 36 and 38may be cladded with one or more materials, for example, to improve theradiopacity of the element without altering the underlying structuralcharacteristics of the base wire (e.g., Nitinol wire cladded in gold).

In some examples, one or both of first and second support structures 36and 38 may include non-metal materials such as one or more syntheticfibers including, for example, at least one of a para-aramid material,liquid crystal polymer (LCP), poly(p-phenylene-2,6-benzobisoxazole),polyether amides, polycarbonates, PTFE, PEEK, ultra-high molecularweight polyethylene, polyethylene naphthalate, polyester, carbon fiber,a glass-fiber reinforced polymer, a carbon-fiber reinforced polymer, orthe like. In some examples, one or both of first and second supportstructures 36 and 38 may include one or more polymers including, forexample, polycarbonate, polyimide, polyetherimide, polyphenylenesulfide, polyether-ether-ketone, one or more fluoropolymers such aspolytetrafluoroethylene, poly(ethene-cotetrafluoroethene), fluorinatedethylene propylene, polyvinylidene fluoride, or the like, one or morethermoplastic polymers such as polyether block amide, a polyamide, apolyamide-based polymer (e.g., nylon), a polyurethane, a polyolefin,PEBAX, polypropylene, a thermoplastic elastomer, one or more thermosetpolymers, or the like. In some examples, one or both of first and secondsupport structures 36 and 38 may include substantially hard and/or rigidbased polymer materials including, for example, Kevlar, LCP, nylon,ultra-high molecular weight polyethylene, FPEN, polyester, glass-fiberreinforced or carbon-fiber reinforced polymers, or the like that may beused to provide columnar and or hoop strength to elongated body 22. Insome examples, forming one or both of first and second supportstructures 36 and 38 using a thermoplastic polymer may help improve theflexibility of the elongated body 22.

Elongated body 12 also includes outer jacket 32 positioned over firstand second support structures 36 and 38 and inner liner 28, the one orboth of first and second support structures 36 and 38 being betweeninner liner 28 and outer jacket 32 in at least some portions ofelongated body 22. In some examples, outer jacket 32 may includepolymeric materials, such as, for example, a polyamide, a polyetherblock amide such as Pebax® commercially available from Arkema Group ofColombes, France, a polyurethane elastomer such as PolyBlend 1100™available from AdvanSource Biomaterials of St. Wilmington, Mass., apolyolefin elastomer (e.g., Engage™ polyolefin elastomer available fromDow Chemical Company of Midland, Mich.), a thermoplastic polyurethanessuch as Pellethane® TPU available from The Lubrizol Corporation ofWickliffe, Ohio, or the like.

In the example of FIG. 2, distal end 50 of outer jacket 32 issubstantially aligned (e.g., aligned so as to be coterminous or nearlyaligned to the extent permitted by manufacturing variances) with distalend 48 of inner liner 28. This may be a result of the technique used toform catheter 20, which may include attaching outer jacket 32 to innerliner 28, then cutting outer jacket 32 and inner liner 28 in a singleoperation. In other examples, outer jacket 32 may extend slightly distalof distal end 48 of inner liner 28. The portion of outer jacket 32 thatextends distal of distal end 48 of inner liner 28 may define the innerdiameter for that portion of catheter 20.

In some examples, at least a portion of an outer surface of outer jacket32 includes one or more coatings, such as, but not limited to, ananti-thrombogenic coating, which may help reduce the formation ofthrombi in vivo, an anti-microbial coating, and/or a lubricatingcoating. The lubricating coating may be configured to reduce staticfriction and/kinetic friction between elongated body 22 and tissue ofthe patient as elongated body 22 is advanced through the vasculature ofthe patient. The lubricating coating can be, for example, a hydrophiliccoating. In some examples, the entire working length of elongated body22 (from distal portion 14B of hub 14 (FIG. 1) to distal end 30) may becoated with the hydrophilic coating. In other examples, only a portionof the working length of elongated body 22 may be coated with thehydrophilic coating. This may provide a length of elongated body 22distal to distal end 14B of hub 14 with which the clinician may gripelongated body 22, e.g., to rotate elongated body 22 or push elongatedbody 22 through the vasculature of the patient.

In some examples, elongate body 22 may include one or more marker bands,such as distal marker band 40, that may be in the form of a full orpartial ring of material that is more radiopaque than all or some of thematerial forming the remainder of elongated body 22. In some examples,distal marker band 40 may include radiopaque materials that allowelongated body 22 (e.g., distal end 30) to be easily observed by theclinician as catheter 20 is advanced through the vasculature of apatient. Suitable radiopaque materials may include, for example, gold,platinum/iridium alloy, palladium, or the like. In some examples, distalmarker band 40 may be positioned over a distal portion of first supportstructure 36, second support structure 38, or both.

Distal marker band 40 may be attached to inner liner 28, outer jacket32, or both. For example, as shown in FIG. 2, a distal part 42 of outerjacket 32 may taper over a distal end of distal marker band 40 to attachto a distal part 44 of inner liner 28. The attachment of distal part 42of outer jacket 32 to distal part 44 of inner liner 44 may help restrainfirst support structure 36, second support structure 38, and distalmarker band 40 in place. In addition, in some examples, distal markerband 40 may be positioned over one or both of first support structure 36or second support structure 38, such that distal marker band 40 ispositioned between a part of one or both of first support structure 36or second support structure 38 and outer jacket 32. In the example shownin FIG. 2, distal marker band 40 is positioned between first supportstructure 36 and outer jacket 32. This may enable distal marker band 40to help maintain first support structure 36 in contact with inner liner28, e.g., during manufacturing of catheter 20, may reduce an outerdiameter of catheter 20 compared to a catheter in which distal markerband 40 is radially outward of both first support structure 36 andsecond support structure 38, or both.

Elongated body 22 has a suitable working length for accessing a targettissue site within the patient from a vascular access point. In someexamples the working length of elongated body 22 may be measured fromhub distal end 14B (FIG. 1; marked by the distal end of optional strainrelief body 11) to distal end 30 of elongated body 22 along longitudinalaxis 26. The working length of elongated body 22 may depend on thelocation of the target tissue and/or the medical procedure for whichcatheter 20 is used. For example, if catheter 20 is a distal accesscatheter or other catheter used to access vasculature in a brain of apatient from a femoral artery access point at the groin of the patient,elongated body 22 may have a working length of about 120 cm to about 135cm, such as about 132 cm, although other lengths may be used. In otherexamples, or for other applications, the working length of elongatedbody 22 may be different.

In some examples, elongated body 22 may define an outer diameter taper(e.g., gradient, gradation, segmented gradient or gradation, or thelike) along its working length of elongated body 22. An outer diameter(OD) taper may assist with the navigability and/or maneuverability ofelongated body 22 through the vasculature of a patient. In someexamples, at least a part (e.g., only part of the working length or theentire working length) of elongated body 22 may define a constant outerdiameter. In such examples, first and second support structures 36 and38 of elongated body 22 may be configured to provide sufficient supportto elongated body 22 to allow the outer diameter of the elongate body 22to remain relatively small along the length of elongated body 22 for agiven inner diameter of elongated body 22 to facilitate distalflexibility about distal portion 20B while still retaining sufficientstrength and pushability about the proximal portion of elongated body22. Additionally, or alternatively, a relatively small OD of elongatedbody 22 may allow for easier to navigability of the catheter 20 throughtortuous vasculature of a patient.

In some examples, catheter 20 may be advanced to a target locationwithin vasculature of the patient in cooperation with a guide member(not shown) such as a guidewire, an inner catheter, both a guidewire andan inner catheter, or the like, which may aid in the navigation (e.g.,steering and manipulation) of elongated body 22 through the vasculature.For example, at least part of inner lumen 24 of elongated body 22 may beconfigured to receive a guide member, such that elongated body 22 may beguided through vasculature over the guide member or the inner catheter.In some examples, the design of distal portion 20B of elongated body 22(e.g., the region defined by distal opening 34) may be configured toresist geometric deformation (e.g., kinking, ovalization, or the like)from forces applied to the distal tip by the guidewire or innercatheter. This resistance to geometric deformation may help improve theease with which elongated body 22 may be guided to a relatively distaltissue site, e.g., through relatively tight turns in the vasculatureand/or the responsiveness of catheter 20 as a clinician guides thedistal tip of elongated body 22 through the vasculature of a patient.

In some examples, elongated body 22 may include tip jacket 46, whichsurrounds distal part 42 of outer jacket 32 and extends beyond a distalend 48 of inner liner 28 and a distal end 50 of outer jacket 32. Inparticular, tip jacket 46 extends longitudinally beyond distal end 48 ofinner liner 28 and distal end 50 of outer jacket 32. Tip jacket 46 thusmay define a single-layer tip of elongated body 22 of catheter 20 thatexcludes inner liner 28 and outer jacket 32.

A distal end of tip jacket 46 defines distal end 30 of catheter 20.Distal end 30 may be a length L1 from the distal end of marker band 40.The distance between the distal end of marker band 40 and distal end 30may depend at least in part on the OD of catheter 20. For example, acatheter 20 with a larger OD may include a larger length L1, while acatheter 20 with a smaller OD may include a smaller length L1. In someexamples, the length L1 between distal end 30 and the distal end ofmarker band 40 may be between about 0.5 mm and about 1.5 mm.

As shown in FIG. 2, tip jacket 46 may overlap the distal part 42 ofouter jacket 32, the distal part 44 of inner liner 28, or both. Aremaining portion of tip jacket 46 may define the only layer of elongatebody 22 of catheter 20 distally of the overlap with the distal part 42of outer jacket 32, the distal part 44 of inner liner 28, or both. Thisremaining portion of tip jacket 46 has a length L2. Length L2 may berelated to length L1. For example, length L2 may be between about ⅓ andabout ½ of L1. As such, in some examples, length L2 may be between about0.1 mm and about 0.8 mm.

A radially outer surface of tip jacket 46 tapers radially inward as tipjacket 46 extends distally, which may reduce the cross-sectional area ofelongate body 22 of catheter 20 near distal end 30 of catheter 20 andaid navigation of catheter 20 through vasculature of a patient. Formingthe distal-most portion of catheter 20 from a single layer of materialmay enable the distal-most portion to be more acutely tapered, which mayalso aid navigation of catheter 20 through vasculature of a patient.

The material from which tip jacket 46 is formed may be the same or alower durometer than the material from which inner liner 28 is formedand the material from which outer jacket 32 is formed. For example, tipjacket 46 may be formed from a polymeric material with a durometer thatis less than 35 D, such as between about 30 A and about 35 D, althoughin other examples, the material of tip jacket 46 may have a higherdurometer than 35 D, depending on the durometers of the materials fromwhich inner liner 28 and outer jacket 32 are formed. In some examples,tip jacket 46 may be formed from a polyolefin elastomer; apoly(ether-block-amide), such as a poly(ether-block-amide) availableunder the trade designation PEBAX® from Arkema, Colombes, France; athermoplastic polyurethane, such as a thermoplastic polyurethaneelastomer available under the trade designation PolyBlend™ fromAdvancSource Biomaterials, Wilmington, Mass.; an aromaticpolyether-based thermoplastic polyurethane available under the tradedesignation Tecothane™ from The Lubrizol Corporation, Wickliffe, Ohio; athermoplastic polyurethane available under the trade designationPellethane® from The Lubrizol Corporation; or mixtures thereof. A tipjacket 46 that is softer than the material from which inner liner 28 isformed and the material from which outer jacket 32 is formed may be lesstraumatic than a catheter in which inner liner 28, outer jacket 32, orboth extend to distal end 30 of catheter 20.

In some examples, instead of or in addition to a tip jacket 46, a distaltip may include a preferential bending location proximal of a distalmarker band. The preferential bending location also may facilitateguiding the catheter through vasculature of a patient and make thecatheter less traumatic upon contacting tissue of the patient. FIG. 3 isa conceptual axial cross-sectional view of another example of a distalportion 60B of an example catheter 60 (e.g., distal portion 17B ofcatheter 10). Distal portion 60B of catheter 60 may be similar to orsubstantially the same as distal portion 20B of catheter 20 of FIG. 2,aside from the differences described herein. For example, distal portion60B includes an elongate member 62 that defines a central axis 66 andincludes an inner liner 68, a first support structure 76 over innerliner 68, a second support structure 78 over inner liner 68 and overpart of the length of first support structure 76, an outer jacket 72,and a distal marker band 80. Distal portion 60B extends to distal end 70of elongate body 62, which defines a distal opening 74 to inner lumen64. Inner liner 68 extends to distal part 84, which defines distal end88 of inner liner 68, and outer jacket 72 extends to distal part 82,which defines distal end 90 of outer jacket 72. Distal part 84 of innerliner 68 is attached to distal part 82 of outer jacket 72. For example,distal part 84 of inner liner 68 may be directly attached to distal part82 of outer jacket 72 with no intervening layers.

Unlike catheter 20 of FIG. 2, in catheter 60 of FIG. 3, second supportstructure 78 ends proximal to a proximal end 94 of distal marker band80. In particular, a distal end 92 of second support structure 78 isproximal to proximal end 94 of distal marker band 80. The space betweendistal end 92 of second support structure 78 and proximal end 94 ofdistal marker band 80 defines a gap 86, which may be at least partiallyfilled with material from outer jacket 72. In some examples, both secondsupport structure 78 and first support structure 76 end proximal toproximal end 94 of distal marker band 80. Gap 86 defines a location withlower radial and/or flexural stiffness than the portion of catheter 70that includes both first support structure 76 and second supportstructure 78, as outer jacket 72 has a lower stiffness than secondsupport structure 78. Thus, catheter 70 may preferentially bend at gap86 in response to distal tip 70 of catheter 60 contacting an anatomicalstructure, such as a wall of vasculature of a patient, or in response toany force oblique or transverse to the longitudinal axis 66. This mayalso contribute to navigability of catheter 60 through vasculature andmake catheter 60 more atraumatic than a catheter that does not includegap 86.

Gap 86 may define any suitable length L3. The length L3 may beproportional to the OD of elongate body 62, e.g., an elongate body 62with a greater OD may include a longer length L3 and an elongate body 62with a smaller OD may include a smaller length L3. In some examples,length L3 of gap 86 may be between about 0.5 mm and about 5 mm, such asbetween about 0.5 mm and about 1.5 mm. A distance L4 between proximalend 94 of distal marker band 80 and distal tip 70 of catheter 60 may bebetween about 2 mm and about 5 mm, and also may be proportional to theOD of elongate body 62.

In some examples, rather than second support structure 78, which is abraid, ending proximal of distal marker band 80 to define gap 86, afirst support structure that is a coil may end proximal of the distalmarker band. FIG. 4 is a conceptual axial cross-sectional view ofanother example of a distal portion 100B of an example catheter 100(e.g., distal portion 17B of catheter 10). Distal portion 100B ofcatheter 100 may be similar to or substantially the same as distalportion 60B of catheter 60 of FIG. 3, aside from the differencesdescribed herein. For example, distal portion 100B includes an elongatemember 102 that defines a central axis 106 and includes an inner liner108, a first support structure 116 over inner liner 108, a secondsupport structure 118 over inner liner 108 and over first supportstructure 116, an outer jacket 112, and a distal marker band 120. Distalportion 100B extends to distal end 110 of elongate body 102, whichdefines a distal opening 114 to inner lumen 104. Inner liner 108 extendsto distal part 124, which defines distal end 128 of inner liner 108, andouter jacket 112 extends to distal part 122, which defines distal end130 of outer jacket 112. Distal part 124 of inner liner 108 is attachedto distal part 122 of outer jacket 12.

Unlike catheter 60 of FIG. 3, in catheter 100 of FIG. 4, first supportstructure 116 ends proximal to a proximal end 134 of distal marker band120. In particular, a distal end of first support structure 116 islocated proximal to proximal end 134 of distal marker band 120. Thespace between the distal end of first support structure 116 and proximalend 134 of distal marker band 120 defines a gap 126, which may be atleast partially filled with material from outer jacket 112. Gap 126defines a location with lower radial and/or flexural stiffness that theportion of catheter 100 that includes both first support structure 116and second support structure 118, as outer jacket 112 has a lower radialand/or flexural stiffness than first support structure 116. Thus,catheter 100 may preferentially bend at gap 126 in response to distaltip 110 of catheter 100 contacting an anatomical structure, such as awall of vasculature of a patient. This may also contribute tonavigability of catheter 100 through vasculature and make catheter 100more atraumatic than a catheter than that does not include gap 126.

Second support structure 118 extends distally past the distal end offirst support structure 116. In the example shown in FIG. 4, a distalpart 138 of second support structure 118 contacts inner liner 108 and ispositioned between inner liner 108 and distal marker band 120. In thisway, distal marker band 120 may compress second support structure 118 toinner liner 108 and help maintain position of distal part 138 of secondsupport structure 118 relative to inner liner 108. Further, secondsupport structure 118 may compress a distal portion of first supportstructure 116 and help maintain position a distal end of first supportstructure 116 relative to inner liner 108.

In some examples, as shown in FIG. 4, catheter 100 may include both adistal tip formed from a single, relatively soft tip jacket 138 and apreferential bending location (e.g., gap 126) proximal of distal markerband 120. Tip jacket 138 may be similar to or substantially the same astip jacket 46 of catheter 20 of FIG. 2.

The catheters described herein can be formed using any suitabletechnique. FIG. 5 is a flow diagram of an example method of forming acatheter as described herein. The technique of FIG. 5 is described withrespect to catheter 20 of FIG. 2; however, the techniques may be used toform other catheters or the catheters described herein (e.g., catheter100) may be formed using techniques other than those described in FIG.5.

In the technique shown in FIG. 5, inner liner 28 may be positioned overa mandrel (142). Inner liner 28 may be fabricated using any suitabletechnique. In some examples, inner liner 28 may be formed using anextrusion process in which the polymeric materials and, if applicable,slip agent, are mechanically mixed together and heated to the meltingpoint of the underlying polymeric material and passed through a tubularextrusion process to form a tubular body having the desired thicknessand diameter profiles. In some examples in which inner liner 28 includesmultiple sections, the respective sections may be positioned over amandrel followed by being subsequently joined together (e.g., fused).

In some examples, after positioning inner liner 28 over the mandrel,inner liner 28 may be heat shrunk onto the mandrel such that inner liner28 conforms to the outer surface of the mandrel and acquire a taperedprofile (if applicable) of the mandrel. In some such examples in whichinner liner 28 includes multiple sections, the respective sections ofinner liner 28 may be sized such that the inner diameter of therespective liner sections are slightly oversized to facilitate placementof the liner sections on the mandrel prior to the heat shrink process.In other examples, however, heat shrinking may not be necessary. Forexample, in addition to, or instead of, heat shrinking, inner liner 28may be longitudinally stretched over the mandrel to substantiallyconform to the outer surface of the mandrel. In either example, innerliner 28 may define a constant inner diameter or may have differentinner diameters, e.g., corresponding to the outer diameters defined bythe mandrel.

After positioning inner liner 28 over a mandrel (142), at least onesupport structure may be positioned over inner liner 28 (144). The atleast one support structure may include one or more of a coil, a braid,or combinations thereof. In some examples, the at least one supportstructure may include a first support structure 36 and a second supportstructure 38. First support structure 36 may include a coil and secondsupport structure 38 may include a braid. In some examples, secondsupport structure 38 may be positioned over first support structure 36.In other examples, first support structure 36 may be positioned oversecond support structure 38.

In some examples, the structural configuration of the at least onesupport structure may be at least partially defined prior to beingpositioned over inner liner 28. For example, a shape memory wire (e.g.,NiTi alloy) or a wire of an otherwise heat-settable metal, alloy, orpolymer base may be wound over a different mandrel where the wires areheat set to define at least one of the desired pitch, spacing, winddiameter, tapering profile, or length of the at least one supportstructure.

After being heat set, the one or more wires of the at least one supportstructure may then be subsequently unwound from the mandrel onto a reelor a bobbin (not shown), and then re-wound/woven over inner liner 28. Insome examples, defining some or all of the structural characteristics ofthe at least one support structure prior to positioning the at least onesupport structure over inner liner 28 may help control the structuralcharacteristics of the at least one support structure (e.g., gapspacings, pitch, etc.), as well as control product consistency anduniformity of the at least one support structure used in multiplecatheters. In addition, shape-setting wires of the at least one supportstructure on a separate, heat-resistant mandrel enables the constructionof the elongated body 22 using the at least one support structure on amandrel made of, for example, PTFE or other lubricious, non-heatresistant materials.

The at least one support structure may be secured in place relative toinner liner 28 using any suitable technique. For example, the at leastone support structure may be adhered to inner liner 28. In someexamples, an adhesive may be positioned over inner liner 28 prior topositioning the at least one support structure over inner liner 28. Inaddition to, or instead of, an adhesive, outer jacket 22, distal markerband 40, or both may be used to secure the at least one supportstructure to inner liner 28. For example, distal marker band 40 may bepositioned over a distal part of first support structure 36 as shown inFIG. 2. In some examples, distal marker band 40 can be adhered to innerliner 28, first support structure 36, or both, or may be held in placewithin elongated body 22 because of being positioned between firstsupport structure 36 and outer jacket 32.

In the technique of FIG. 5 also includes positioning outer jacket 32over the at least one support structure (146), including the optionaldistal marker band 40, and inner liner 28. Distal part 42 of outerjacket 32 then may be bonded to distal part 44 of inner liner 28 (148).In some examples, to join distal part 42 of outer jacket 32 to distalpart 44 of inner liner 28, outer jacket 22 may be heat-shrunk onto innerliner 28 and the at least one support structure, which may result inouter jacket 32 being bonded to inner liner 28 along a length of outerjacket 32. In some examples, the heat shrinking of outer jacket 32 mayhelp secure the respective positions of the at least one supportstructure along elongated body 22. For example, outer jacket 32 mayextend through apertures defined in second support structure 38 andbetween coils or turns of first support structure 36 to contact and bondto inner liner 28 (e.g., using thermal bonding, an adhesive, or thelike). Thus, although a gap is shown between coils or turns of firstsupport structure 36 in FIG. 2, in some examples, these gaps may befilled with material from outer jacket 32, an adhesive, or a combinationof adhesive and material from outer jacket 32. This may help minimizethe wall thickness of elongated body 22 and, therefore, increase the IDof elongated body 22 for a given OD by limiting the inclusion ofaddition layer within the wall construction of elongated body 22. Inaddition, the absence of additional layers (e.g., an adhesive/tie layer)that joins inner liner 28 to outer jacket 32 may contribute to anincreased flexibility of catheter 20.

Tip jacket 46 then may be positioned over distal part 42 of outer jacket32 (150). Tip jacket 46 may be positioned to overlap a tapering portionof outer jacket 32 and may extend beyond distal end 50 of outer jacket32. For example, tip jacket 46 may longitudinally extend beyond distalend 48 of inner liner 28 and distal end 50 of outer jacket 32. Tipjacket 46 then may be bonded to outer jacket 32 (152). For example, tipjacket 46 may be heat-shrunk onto distal part 42 of outer jacket 32. Asshown in FIG. 2, a distal portion of tip jacket 46 may shrink to contactthe mandrel and define a portion of the inner diameter of catheter 20.The distal portion of tip jacket 46 also may define a single layer tipof catheter 20. A radially outer surface of tip jacket 46 may taperradially inward as tip jacket 46 extends distally, and tip jacket 46 maybe formed from a material that is the same or a lower durometer than thematerial from which inner liner 28 is formed and the material from whichouter jacket 32 is formed. In this way, tip jacket 46 may be moreatraumatic than a catheter 20 in which inner liner 28, outer jacket 32,or both extend to a distal end of catheter 20.

Once elongated body 22 is formed, hub 14 (FIG. 1) may be attached to theproximal end of elongated body 22 (e.g., proximal end 12A of elongatedbody 12 of FIG. 1) using any suitable technique, such as an adhesive,fusing, over-molding, or any combination thereof.

FIG. 6 is a flow diagram of another example method of forming a catheteras described herein. The technique of FIG. 6 is described with respectto catheter 60 of FIG. 3; however, the techniques may be used to formother catheters or the catheters described herein (e.g., catheter 100)may be formed using techniques other than those described in FIG. 6.

In the technique shown in FIG. 6, inner liner 68 may be positioned overa mandrel (162). This step may be similar to or substantially the sameas step (142) of FIG. 5.

After positioning inner liner 68 over the mandrel (162), a first supportstructure 76 may be positioned over inner liner 68 (164). First supportstructure 76 may include a coil, a braid, or the like. In the exampleillustrated in FIG. 3, first support structure 76 includes a coil. Insome examples, the structural configuration of first support structure76 may be at least partially defined prior to being positioned overinner liner 68. For example, a shape memory wire (e.g., NiTi alloy) or awire of an otherwise heat-settable metal, alloy, or polymer base may bewound over a different mandrel where the wires are heat set to define atleast one of the desired pitch, spacing, wind diameter, taperingprofile, or length of first support structure 76.

After being heat set, the one or more wires of first support structure76 may then be subsequently unwound from the mandrel onto a reel or abobbin (not shown), and then re-wound/woven over inner liner 68. In someexamples, defining some or all of the structural characteristics offirst support structure 76 prior to positioning first support structure76 over inner liner 68 may help control the structural characteristicsof first support structure 76 (e.g., gap spacings, pitch, etc.), as wellas control product consistency and uniformity of first support structure76 used in multiple catheters. In addition, shape-setting wires of firstsupport structure 76 on a separate, heat-resistant mandrel enables theconstruction of the elongated body 62 using first support structure 76on a mandrel made of, for example, PTFE or other lubricious, non-heatresistant materials.

In some examples, first support structure 76 may be secured in placerelative to inner liner 68 using an adhesive. In other examples, firstsupport structure 76 may be secured in place relative to inner liner 68by another structure of elongate body 62, such as, for examples, distalmarker band, second support structure 78, or outer jacket 72.

In the technique of FIG. 6 also includes positioning second supportstructure 78 over first support structure 76 (166). Second supportstructure 78 may include a coil, a braid, or the like. In the exampleillustrated in FIG. 3, second support structure 78 includes a braid. Insome examples, second support structure 78 may be sized with an innerdiameter slightly smaller than an outer diameter of first supportstructure 76 and may help maintain first support structure 76 inposition relative to inner liner 68.

Distal marker band 80 is positioned over a distal part of one of firstsupport structure 76 or second support structure 78 (168). In someexamples, distal marker band 80 may be positioned over the distal partof one of first support structure 76 or second support structure 78(168) after second support structure is positioned over first supportstructure 76 (166). The other of first support structure 76 or secondsupport structure 78 may end proximal to distal marker band 80. In otherexamples, distal marker band 80 may be positioned over the distal partof first support structure 76 (168) before second support structure 78is positioned over first support structure 76 (e.g., in examples inwhich second support structure 78 does not cover a distal part of firstsupport structure 76). Distal marker band 80 may help maintain positionof the distal part of the one of first support structure 76 or secondsupport structure 78 over which distal maker band 80 is positionedrelative to inner liner 68. In some examples, distal marker band 80 maybe adhered to the one of first support structure 76 or second supportstructure 78, inner liner 68, or both. In other examples, distal markerband 80 may simply be fit over the distal part of one of first supportstructure 76 or second support structure 78. For example, a distal endof the other of first support structure 76 or second support structure78 may be proximal to a proximal end of distal marker band 80, thusdefining gap 86. Gap 86 defines a location with lower radial and/orflexural stiffness than the portion of catheter 70 that includes bothfirst support structure 76 and second support structure 78 due to theabsence of one of first support structure 76 or second support structure78. As discussed above, gap 86 may define any suitable length L3. Thelength L3 may be proportional to the OD of elongate body 62, e.g., anelongate body 62 with a greater OD may include a longer length L3 and anelongate body 62 with a smaller OD may include a smaller length L3. Insome examples, length L3 of gap 86 may be between about 0.5 mm and about5 mm. A distance L4 between proximal end 94 of distal marker band 80 anddistal tip 70 of catheter 60 may be between about 2 mm and about 5 mm,and also may be proportional to the OD of elongate body 62.

Once distal marker band 80 is positioned over a distal part of one offirst support structure 76 or second support structure 78 (168), outerjacket 72 is positioned over first support structure 76, second supportstructure 78, and distal marker band 80 (170). Distal part 82 of outerjacket 72 then may be bonded to distal part 84 of inner liner 68 (172).In some examples, to bond distal part 82 of outer jacket 72 to distalpart 84 of inner liner 68, outer jacket 72 may be heat-shrunk onto innerliner 68, first support structure 76, second support structure 78, anddistal marker band 80, which may result in outer jacket 72 being bondedto inner liner 68 along a length of outer jacket 72. In some examples,the heat shrinking of outer jacket 72 may help secure the respectivepositions of first support structure 76, second support structure 78,and distal marker band 80 along elongated body 62. For example, outerjacket 72 may extend through apertures defined in second supportstructure 78 and between coils or turns of first support structure 76 tocontact and bond to inner liner 68. Thus, although a gap is shownbetween coils of first support structure 76 in FIG. 2, in some examples,these gaps may be filled with material from outer jacket 72, anadhesive, or a combination of adhesive and material from outer jacket72. This may help minimize the wall thickness of elongated body 62 and,therefore, increase the ID of elongated body 62 for a given OD bylimiting the inclusion of addition layer within the wall construction ofelongated body 62. In addition, the absence of additional layers (e.g.,an adhesive/tie layer) that joins inner liner 68 to outer jacket 72 maycontribute to an increased flexibility of catheter 60.

In some examples, although not shown in FIG. 6, a tip jacket (e.g., tipjacket 136 of FIG. 4) then may be positioned over distal part 82 ofouter jacket 72. The tip jacket may be positioned to overlap a taperingportion of outer jacket 72 and may extend beyond distal end 90 of outerjacket 72. The tip jacket then may be bonded to outer jacket 72. Forexample, the tip jacket may be heat-shrunk onto distal part 82 of outerjacket 72.

In some examples, any of catheter 10, catheter 20, catheter 60, orcatheter 100 may be a part of an assembly that includes, e.g., a guidemember/or an aspiration pump. In some examples, the aspiration pump maybe connected to catheter 10, catheter 20, catheter 60, or catheter 100by an intermediate tube. The guide member may be used to guide catheter10 to a target tissue site within the vasculature of a patient. In someexamples, a method of using catheter 10 comprises introducing a guidemember or an inner catheter into vasculature (e.g., an intracranialblood vessel) of a patient via an access point (e.g., a femoral artery),and guiding elongated body 12 over the guide member. Once distal end 12Bof elongated body 12 is positioned at the target tissue site, which maybe proximal to thromboembolic material (e.g., a thrombus), thethromboembolic material may be removed from the vasculature viaelongated body 12. For example, the thromboembolic material may beaspirated from the vasculature by at least applying a vacuum force toinner lumen 24 of elongated body 12 via hub 14 (and/or proximal end12A), which may cause the thromboembolic material to be introduced intoinner lumen 24 via distal opening 13. Optionally, the vacuum oraspiration can be continued to thereby draw the thromboembolic materialproximally along the inner lumen 24, all or part of the way to theproximal end 12A or hub 14.

As another example, the thromboembolic material may be removed from thevasculature using another technique, such as via an endovascularretrieval device delivered through the inner lumen 24 of the elongatedbody 12. In such a method the elongated body 12 can be inserted into thevasculature (for example using any technique disclosed herein) and theretrieval device advanced through the inner lumen 24 (or through anothercatheter, such as a microcatheter, inserted into the vasculature throughthe inner lumen 24) so that the device engages the thromboembolicmaterial. The retrieval device and the material engaged thereby(together with any other catheter or microcatheter) can then beretracted into the inner lumen 24 and removed from the patient.Optionally, aspiration can be performed with or through the elongatedbody 12 during retraction of the retrieval device and thromboembolicmaterial into the elongated body 12. Optionally the retrieval devicealong with the thrombus could be pulled back into the tip of thecatheter 10 under aspiration and then the retrieval device and catheter10 withdrawn together as one unit toward and through a surroundinglarger sheath or catheter. The vasculature can include neurovasculature,peripheral vasculature or cardiovasculature. The thromboembolic materialmay be located using any suitable technique, such as fluoroscopy,intravascular ultrasound or carotid Doppler imaging techniques.

Various examples have been described. These and other examples arewithin the scope of the following claims.

What is claimed is:
 1. A catheter comprising: an elongated bodyincluding proximal and distal portions, the distal portion of theelongated body comprising: an inner liner; a first support structurepositioned over the inner liner; a second support structure positionedover the first support structure; a marker band, wherein a distalportion of the second support structure extends distally of a distal endof the first support structure, wherein the distal portion of the secondsupport structure contacts the inner liner and is positioned between theinner liner and the distal marker band; an outer jacket positioned overthe first and second support structures, wherein the outer jacket tapersradially inward distal of distal-most parts of the first and secondsupport structures and distally of the distal end of the marker band tobond to the inner liner, and wherein a distal end of the inner liner anda distal end of the outer jacket are substantially aligned; and a tipjacket positioned over a distal part of the outer jacket and extendingbeyond the distal ends of the inner liner and the outer jacket to definea single-layer catheter tip, wherein the tip jacket comprises a materialthat is the same or a lower durometer than the inner liner and the sameor a lower durometer than the outer jacket.
 2. The catheter of claim 1,wherein the tip jacket comprises a polyurethane, a polyolefin elastomer,a poly(ether-block-amide), or combinations thereof.
 3. The catheter ofclaim 1, wherein the tip jacket material has a durometer of 35 D orless.
 4. The catheter of claim 1, wherein the tip jacket is the onlylayer for the distal-most 0.3 to 0.8 millimeters of the catheter.
 5. Thecatheter of claim 1, wherein the inner liner and the outer jacket extenddistally past the distal-most part of the second support structure byabout 0.2 millimeters to about 0.6 millimeters.
 6. The catheter of claim1, wherein the first and second support structures comprise at least oneof a braid or a coil.
 7. The catheter of claim 1, wherein the first andsecond support structures comprise a braid and a coil.
 8. The catheterof claim 7, wherein the braid is positioned over the coil.
 9. Thecatheter of claim 7, wherein the coil is positioned over the braid. 10.The catheter of claim 1, wherein the first support structure ends atleast about 0.5 millimeters proximally of a proximal end of the markerband.
 11. An assembly comprising: a catheter comprising: an elongatedbody including proximal and distal portions, the distal portion of theelongated body comprising: an inner liner; a first support structurepositioned over the inner liner; a second support structure positionedover the first support structure; a marker band, wherein a distalportion of the second support structure extends distally of a distal endof the first support structure, wherein the distal portion of the secondsupport structure contacts the inner liner and is positioned between theinner liner and the distal marker band; an outer jacket positioned overthe first and second support structures, wherein the outer jacket tapersradially inward distal of a distal-most parts of the first and secondsupport structures and distally of the distal end of the marker band tobond to the inner liner, and wherein a distal end of the inner liner anda distal end of the outer jacket are substantially aligned; and a tipjacket positioned over a distal part of the outer jacket and extendingbeyond the distal ends of the inner liner and the outer jacket to definea single-layer catheter tip, wherein the tip jacket comprises a materialthat is the same or a lower durometer than the inner liner and the sameor a lower durometer than the outer jacket; and an aspiration pumpconnected to the catheter.
 12. A catheter comprising: an elongated bodyincluding proximal and distal portions, the distal portion of theelongated body comprising: an inner liner; a first support structurepositioned over the inner liner; a second support structure positionedover the first support structure; a distal marker band positioned over adistal part of the second support structure, wherein the first supportstructure ends proximally of a proximal end of the distal marker band,and wherein the distal part of the second support structure contacts theinner liner and is positioned between the inner liner and the distalmarker band; and an outer jacket positioned over the first supportstructure, the second support structure, and the distal marker band,wherein the outer jacket tapers radially inward distal of a distal-mostpart of the distal marker band to bond to the inner liner.
 13. Thecatheter of claim 12, wherein the first support structure comprises acoil and the second support structure comprises a braid.
 14. Thecatheter of claim 13, wherein a distal end of the coil is proximal tothe proximal end of the distal marker band.
 15. The catheter of claim12, wherein the first support structure comprises a braid and the secondsupport structure comprises a coil.
 16. The catheter of claim 15,wherein a distal end of the braid is proximal to the proximal end of thedistal marker band.
 17. The catheter of claim 12, wherein the firstsupport structure ends at least about 0.5 millimeters proximally of theproximal end of the distal marker band.
 18. The catheter of claim 12,wherein the first support structure ends between about 0.5 millimetersand about 5 millimeters proximally of the proximal end of the distalmarker band.
 19. An assembly comprising: a catheter comprising: anelongated body including proximal and distal portions, the distalportion of the elongated body comprising: an inner liner; a firstsupport structure positioned over the inner liner; a second supportstructure positioned over the first support structure; a distal markerband positioned over a distal part of the second support structure,wherein the first support structure ends proximally of a proximal end ofthe distal marker band, and wherein the distal part of the secondsupport structure contacts the inner liner and is positioned between theinner liner and the distal marker band; and an outer jacket positionedover the first support structure, the second support structure, and themarker band, wherein the outer jacket tapers radially inward distal of adistal-most part of the marker band to bond to the inner liner; and anaspiration pump connected to the catheter.